Is it possible to cut HIV transmission by using antiretroviral treatment? A collection of new articles published in the open-access journal PLoS Medicine, in conjunction with the HIV Modelling Consortium, addresses this pressing question.

The PLoS Medicine articles provide insights into the feasibility of interventions, their potential epidemiological impact and affordability, and recent scientific observational studies and community trials, which will support evidence-based decision-making on the use of antiretroviral treatment to prevent HIV transmission.

The background to this collection comes from a November 2011 meeting in Stellenbosch, South Africa, which focused on the cross-cutting issues that will affect the impact of new scientific findings about HIV treatment preventing new infections. As the introductory article “HIV Treatment as Prevention: Models, Data and Questions Towards Evidence-based Decision-Making” explains, over the past two years there have been several positive advances in HIV prevention research.

In particular, the authors say: “The finding that has created the greatest excitement has been that HIV-infected individuals who are given antiretroviral treatment (ART) are much less likely to transmit the infection to their heterosexual partners than those who are not.” Currently ART is directed at those in greatest clinical need, and expanding the group of people treated would be a substantial change in health policy. It would also have a huge associated cost.

The volume of information needed to make efficient and ethical policy decisions regarding HIV treatment as prevention is vast, and mathematical models can help pull the information together and structure it in a useful way. One focus of the collection is to evaluate the utility of these models by assessing the level of consistency between them – and between the models and data collected from the real world.

The choice of which particular groups to expand access to ART to depends on a wide range of considerations including, for example, which groups are easiest to access and which groups are most likely to reduce onward transmission. Decisions regarding HIV treatment as prevention are not only practical but ethical, argue leading authors in the series; as health policy on HIV prevention is limited by resource constraints, the authors review how to expand the provision of ART and who to expand it to.

This collection, “Investigating the Impact of Treatment on New HIV Infections”, publishes two weeks prior to the AIDS 2012 conference in Washington D.C., which PLoS Medicine editors and collection authors will be attending.